A method for receiving a PTRS by a user equipment (UE) in a wireless communication system may comprise the steps of: receiving first information for configuring one or more bandwidth parts (BWPs); receiving second information including threshold value information relating to a frequency density of a PTRS; receiving downlink control information (DCI), wherein the DCI includes a first field indicating an activated BWP among the one or more BWPs configured on the basis of the first information, and a second field related to a transmission configuration indication (TCI) state; and receiving the PTRS in the activated BWP, wherein the frequency density of the PTRS is determined by the number of resource blocks associated with each TCI state.